1. Field of the Invention
This invention relates to Emergency Position Indicating Radio Beacons (EPIRBs) that are used to send an emergency signal in the case where a ship or vessel is in trouble and is in need of assistance. In particular, it relates to an EPIRB that utilizes the Global Positioning System (GPS) and sends the EPIRB latitude and longitude coordinates in emergency transmissions at 406 MHz.
2. Description of Related Art
The use of EPIRBs for emergency signaling by vessels in distress is well known in the marine industry. Typically an EPIRB is a RF transmitter that emits signals on one or more frequencies, normally an emergency band frequency, to notify satellites, surrounding ships, and aircraft in the area that a vessel is in trouble. EPIRBs can be either manually activated or automatically activated by contact with ocean or fresh water. Also known is the use of a GPS receiver that can provide very accurate latitude and longitude geographical positions of location. Typically, three or more satellites in orbit provide triangulation to the hand-held or ship installed unit giving instantaneous and continuous latitude and longitude information of the EPIRB.
Although the basic operation of GPS-enabled EPIRBs by ships or vessels in distress has proven to save lives, the devices in use today are transmit-only signaling devices. Furthermore, many times these EPIRBs get activated far out to sea, where no other means of communications are feasible. As such there typically exists no receive communications path through which the vessel operator or captain could receive back a confirmation message acknowledging that the emergency beacon's message has been received by the rescue satellite network.
Another limitation of the present-day EPIRB is its user interface. U.S. Patent Application 2007/0232275 which was published Oct. 4, 2007 for a “Global Bi-directional Locator Beacon And Emergency Communication System” discloses an emergency monitoring reporting system that also provides for bi-directional short text messages that can be remotely monitored between the user and monitoring system. This pending patent application does not disclose or teach having an EPIRB that itself includes a display screen and a transmitter for transmitting text messages from the user.
What is needed is a device with an integrated wireless receiver within the EPIRB that can be used as a return message pathway while at the same time providing a display apparatus to visually indicate the content of any return message received. Ideally, this display apparatus would provide an enhanced user interface, allowing visual alpha numeric display of EPIRB status information such as: operational status, GPS lock, GPS coordinate position, transmitting, receiving, battery life gauge, message received, and other useful information.
In U.S. Pat. No. 6,388,617, Flood et al. describes an EPIRB with an external interface for use with an external GPS receiver the disclosure of which is integrated herein. This interface is typically implemented as an Infrared (IR) sensor and utilizes an electro/optical circuit to transfer the data from the GPS unit to the EPIRB. A limitation of this EPIRB using an IR interface to input external GPS coordinates is the degraded performance due to the wide range of required operating background lighting conditions, from bright sunlight to pitch black at nighttime. Applicant hereby incorporates the subject matter in U.S. Pat. No. 6,388,617 by reference.
What is needed is a device that includes an Automatic Background Light Adjustment algorithm for adjusting the IR sensor light level as a function of the background light conditions in order to improve the sensor's effectiveness. Additionally, what is needed is circuitry to allow the EPIRB to use either a supplied external GPS source (Flood et. al.), an internal GPS coordinate calculation, or both.